Conventionally, a wheel loader is known as a work machine. In a wheel loader, an attachment such as a bucket is provided at a front end of a boom pivoted on a vehicle body, and the boom is provided so as to be movable upward and downward by a boom cylinder, and the bucket is driven via a Z-bar link.
As shown in FIG. 12, the Z-bar link includes: a bell crank 11 rotatably pivoted substantially at the center of a boom 10; a tilt cylinder (refer to the dotted chain line) connecting an upper end side of the bell crank 11 and the not-shown vehicle body; and a connecting link 13 for connecting a lower end side of the bell crank 11 and a back portion of a bucket 20.
Note that, in FIG. 12, the boom cylinder and the tilt cylinder are not shown to prevent the figure from being complicated. In addition, a pivotal position (pivot position) Z of the tilt cylinder on a working structure of the vehicle body is illustrated on the boom 10 in the figure. However, the pivoted position Z is actually on the not-shown vehicle body, not on the boom 10. Further, in FIG. 12, states of the bucket 20 at a ground position, at an intermediate position, and at a top position being uppermost are shown.
In the wheel loader having the above-mentioned structure, the bucket 20 is positioned in the vicinity of the ground position to perform digging work, and is positioned at the intermediate position or the top position to be allowed to perform dumping onto a truck.
In addition to the digging work, sometimes the wheel loader is used to scoop mud, animal waste, or the like. In this case, as shown in FIG. 12, the bucket 20 is tilted at the ground position so as not to spill the mud or the like having fluidity, to thereby efficiently perform scooping.
With regard to the wheel loaders of this kind, a wheel loader is also known in which a fork is combined with the Z-bar link (for example, Patent Document 1).
As shown in FIG. 13, according to the wheel loader, a bucket 20 can be replaced with a fork 30, and when replacing, a not-shown tilt cylinder is substantially extended so as to mount the fork 30. That is, an extension amount of the tilt cylinder corresponds to, as shown in the double-dotted chain line, an offset angle a of the bucket 20, and the fork 30 is mounted to a connecting link 13 at this position.
Accordingly, even in the wheel loader using the Z-bar link, the attachment angle from the ground position to the top position is kept substantially constantly, and an angle characteristic is improved, thereby enabling the work using the fork 30.
[Patent Document 1] JP-A-Sho63-22499